something is killing my shrimp and attacking my fish

Ok recently I had a couple of disappearances.

Disappearances:
Two peppermint shrimps (not sure how long MIA)
Skunk cleaner shrimp (1-2 days MIA)

Wounded fish:
Royal Gramma has scratch/bruise on right side.
One Chromis has a very bad bruise on his right side by near the top. Looks like it might be a bite from another fish?

Stock list is:
Rabbitfish
Yellow Tang
Royal Gramma
PJ Cardinal
2- Clown Fish
4- Green Chromis
Fire Fish

I would suspect the Royal Gramma of the shrimp disappearances but they have lived together for a long time, and the shrimp were as large as the RG. Also doesn't explain his wound.

Only thing I have added recently that could contain a hitch hiker is a mushroom rock from a very reliable LFS, which I of course did not QT, thinking it couldn't possibly have anything bad. Not positive it did contain a hitch hiker, but I noticed a cavity behind a mushroom something could have hid in.

I have been watching closely at night with a flash light can't find anything, no popping sounds or anything (I have a pet mantis so I would know a mantis click if I heard one).

Also all the wounded fish sleep in the same relative area at night. which is a large grouping of live rock with a network of small tunnels leading in all directions. Most of which it is impossible to see all the way through.

Do you think I have a hitch hiker that is killing stuff, or is it the RG eating them and the wounded fish a coincidence?

 

It could be a fire worm. I don't think its the rg as I have a large one and mine don't mess with anything in my tank to include shrimp

 

i think the RG is eating the shrimp and one of the other fish is bullying the wounded fish.

 

Stepho
possibly a crab? sneaks up on stuff while they are dormant

or
RG damages itself during the eating process , chasing the shrimp
Chromis fancies some of the half eaten snack and RG takes exception to this

Steve

 

Sounds like a crab of some sort. Is your Mantis in the same tank? If so, that could be your suspect.



Luna

 

+1 on the gramma as you already suspect, and possibly the Yellow Tang could be bullying, they are known for it.

 

The mantis is in his own tank.

I would suspect a hitch hiker crab, but the only thing I added recently is a small mushroom rock with one little cavity. I don't think a crab could fit in it that could take out my shrimp/fish.

The hole is big enough for a mantis, but I doubt he would be taking shrimp/fish as the tank is stocked with hermits and snails. Also doubting a mantis because having watched mine attempt to catch a damsel I just don't see it happening unless it is a nocturnal variety.

I guess for now I will assume the RG did it and the fish were wounded by another fish (YT most likely), but keep a close eye on the tank.